﻿// Copyright 2004-2011 Castle Project - http://www.castleproject.org/
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// 
//     http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#region 导入名称空间

using System;
using System.Collections.Generic;
using System.Diagnostics;
using LightWork.DynamicProxy.Generators;
using LightWork.DynamicProxy.Generators.Emitters;

#endregion

namespace LightWork.DynamicProxy.Contributors
{
    public class DelegateProxyTargetContributor : CompositeTypeContributor
    {
        private readonly Type targetType;

        public DelegateProxyTargetContributor(Type targetType, INamingScope namingScope) :
            base(namingScope)
        {
            this.targetType = targetType;
        }

        protected override IEnumerable<MembersCollector> CollectElementsToProxyInternal(IProxyGenerationHook hook)
        {
            Debug.Assert(hook != null, "hook != null");
            var targetItem = new DelegateMembersCollector(targetType)
            {
                Logger = Logger
            };
            targetItem.CollectMembersToProxy(hook);
            yield return targetItem;
        }

        protected override MethodGenerator GetMethodGenerator(MetaMethod method, ClassEmitter @class,
            ProxyGenerationOptions options,
            OverrideMethodDelegate overrideMethod)
        {
            var invocation = GetInvocationType(method, @class, options);
            return new MethodWithInvocationGenerator(method,
                @class.GetField("__interceptors"),
                invocation,
                (c, m) => c.GetField("__target").ToExpression(),
                overrideMethod,
                null);
        }

        private Type GetInvocationType(MetaMethod method, ClassEmitter emitter, ProxyGenerationOptions options)
        {
            var scope = emitter.ModuleScope;
            var key = new CacheKey(method.Method, CompositionInvocationTypeGenerator.BaseType, null, null);

            // no locking required as we're already within a lock
            var invocation = scope.GetFromCache(key);
            if (invocation != null)
                return invocation;

            invocation = new CompositionInvocationTypeGenerator(method.Method.DeclaringType,
                    method,
                    method.Method,
                    false,
                    null)
                .Generate(emitter, options, namingScope)
                .BuildType();

            scope.RegisterInCache(key, invocation);

            return invocation;
        }
    }
}